Our invention relates to apparatus for data transfer with disklike record media in general and, in particular, to such apparatus of the kind known as a Winchester drive wherein a relatively rigid magnetic disk or disks are semipermanently mounted on a drive spindle and normally held in contact with a magnetic transducer or transducers, the latter moving out of contact with the disk or disks upon rotation thereof for data transfer. Still more specifically, our invention pertains to a mechanism for use in such apparatus for retracting the transducer or transducers from the data storage region to the non-storage region of the disk or disks when the apparatus is electrically turned off.
The Winchester drive disk is known wherein at least one, usually two or more, relatively rigid magnetic disks and associated transducers are semipermanently enclosed in a dustproof housing for data transfer in a dustfree environment. The transducers are spring biased into contact with the magnetic disks. Upon rotation of the disks the streams of air created thereby cause the transducers to move out of contact with the disks again the bias of the springs. The transducers write or read data on or from the disks while being thus spaced a minimal distance therefrom, so that during the process of data transfer, the transducers and disks are not subjected to any frictional wear.
However, both at the beginning and end of each run of data transfer, the transducers must slide over the disks, with the possibility of ruining the disks or being ruined thereby. One conventional solution to this problem is found in Hayakawa U.S. Pat. No. 4,593,329 assigned to the assignee of our instant application. This patent teaches how to electrically control the stepping motor, at the end of each run of data transfer, so as to retract the transducer radially toward the center spindle from the storage region of the magnetic disk. The transducer lands on the disk, only after it has been retracted. Japanese Laid Open Utility Model Application No. 60-40066 also teaches to hold the transducer retracted on the magnetic disk when the latter is out of rotation.
We object to both of these known solutions because the transducer is retracted by the stepping motor or equivalent electric transducer positioning motor. Such a motor becomes deenergized, of course, when the disk drive is unexpectedly powered off, as in the event of a power failure or other accident. Then the transducer will slide over and land on the data storage region of the magnetic disk. An additional objection is that both known solutions require the production of a control signal for transducer retraction, making the circuitry of the disk drive complex and expensive.